Phytoplankton community in a tropical estuarine gradient after an exceptional harmful bloom of Akashiwo sanguinea (Dinophyceae) in the Todos os Santos Bay
The objective of this study was to evaluate variations in the composition and abundance of the phytoplankton community after an exceptional harmful bloom of Akashiwo sanguinea that occurred in Todos os Santos Bay (BTS) in early March, 2007. Samples were collected every ten days, between April, 2007...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Instituto Oceanográfico da Universidade de São Paulo
2024-04-01
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| Series: | Ocean and Coastal Research |
| Subjects: | |
| Online Access: | https://www.journals.usp.br/ocr/article/view/224227 |
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| Summary: | The objective of this study was to evaluate variations in the composition and abundance of the phytoplankton community after
an exceptional harmful bloom of Akashiwo sanguinea that occurred in Todos os Santos Bay (BTS) in early March, 2007. Samples
were collected every ten days, between April, 2007 and March, 2008, from the estuarine gradient of the Paraguaçu River to BTS. The
physical and chemical variables were measured in situ using a multiparameter sensor. Water samples were collected for analysis
of the dissolved inorganic nutrient concentrations and for the study of composition and abundance of the microphytoplankton.
Overall, 135 taxa were identified, with a higher richness of diatoms. The total cell density ranged from 2.92 × 103
to 1.16 × 107
(5.47 × 105
± 1.69 × 106
) cells L−1, with higher values in the freshwater zone than in the marine area. Five species showed peaks of
abundance throughout the study, forming small blooms. Four of these blooms occurred in the rainy season, formed by the species
Guinardia striata (April, 2007), Scrippsiella cf. acuminata (August, 2007), Euglena gracilis (August, 2007), and Skeletonema cf. costatum
(September, 2007), while a new bloom of the species Akashiwo sanguinea occurred during the dry season (December, 2007). The
environment was typically oligotrophic, with low spatiotemporal variation in the concentrations of dissolved nutrients. Even so, we
observed short-term variations in the structure and composition of the phytoplankton community, demonstrated by rapid bloom
events, followed by an increase in the total abundance of microphytoplankton, especially during the rainy season. The blooms did
not cause any notable changes in the water column and did not present any harmful effects on the system.
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| ISSN: | 2675-2824 |